Since there are multiple redundant copies of the transactions database, no one can seize bitcoins. The most someone can do is force the user, by other means, to send the the bitcoins to someone else. This means that governments cant freeze someones wealth, and thus users of Bitcoins will have complete freedom to do anything they want with their money.
Unless users publicize their wallet addresses publicly, no one can trace transactions back to them. No one, other than the wallet owners, will know how many Bitcoins they have. Even if the wallet address was publicized, a new wallet address can be easily generated.
Once Bitcoins are sent, the transaction cannot be reversed. Since the ownership address of Bitcoins will be changed to the new owner, once it is changed, it is impossible to revert. Since only the new owner has the associated private key, only he/she can change ownership of the coins. This ensures that there is no risk involved when receiving Bitcoins.